The proposed investigation is a continuation of the ongoing NEAD study, which addresses an important health care issue for women and their children. The use of antiepileptic drugs (AEDs) in women of childbearing age for epilepsy and for other indications (e.g., pain and psychiatric disorders) is common, but physicians need additional data, which are critical to adequately advise and direct treatment in these women. Animal studies have clearly demonstrated that commonly employed AEDs impair behavioral neurodevelopment. The potential consequences of such cognitive and behavioral deficits in humans are severe in terms of both personal and societal costs. However, controversy exists on the following issue to be addressed by this proposal. Do the most commonly used AEDs have differential effects on neurobehavioral outcomes in children exposed in utero? The primary objective of this study is to differentiate the relative risks/benefits of the four most commonly used AEDs in the treatment of women with epilepsy in terms of their children's neurobehavioral development after in utero exposure to AED monotherapy (carbamazepine, lamotrigine, phenytoin, or valproate). The NEAD study is a prospective, parallel-group, cohort design, multicenter investigation. The major strength of the NEAD study is that it has enrolled a large and unique cohort of 323 mother/child pairs during pregnancy and collected prospective data on factors, which could affect neurobehavioral outcome. The primary outcome variables are IQ scores of the children and other measures of neurobehavioral development at 6 years/old. This grant extension is designed to follow the children to 6 years/old at which time neurobehavioral measures predict school performance and ultimate adult IQ. Samples have and will be collected for future pharmacogenetic investigations. The NEAD study has an invaluable cohort, and the results of this continuation proposal will impact the clinical management of women receiving these medications, and improve the health of their children.